Influence of electron damping and reservoir on the magnetic phase diagram of chromium alloys

The magnetic phase diagram of chromium alloys sensitively depends on both electron damping and the presence of an electron reservoir. If the damping energy Γ vanishes and the power ρ of the reservoir is infinite, then lightly doped CrMn alloys would experience a first-order transition from an incommensurate (I) to a commensurate (C) spin-density wave (SDW) state with decreasing temperature. Either damping or a finite reservoir may flip the phase boundary from one side of the triple point to the other, allowing a commensurate-to-incommensurate transition with decreasing temperature as observed experimentally. Both damping and a finite reservoir suppress the first-order jumps in the SDW order parameter and wave vector. When ρ≤2, the C-I transition is second order for all temperatures. When ρ≳2, the transition is second order near the tricritical point but first order at lower temperatures. Unlike electron damping, an electron reservoir does not shift the paramagnetic phase boundary and triple point.